The determination of deformation of soil nailed structures by a simplified method

This paper presents the results of research to develop a simple method of determining deformation at the crest of a soil nailed wall. At the present time there is no established simplified method for accurately predicting soil nail walls deformation, with the current predictive methods being either an empirical approach or based on the use of numerical analysis. By carrying out a parametric study through the use of the finite element program PLAXIS, the effects of soil nail inclination, spacing and length, as well as the soil properties of stiffness and strength on soil nail wall deformation were assessed. The results indicated that although all of these elements had some ef-fect on deformation, soil effective cohesion had the greatest effect. The results were used to create two empirical prediction formulae and a series of design charts to determine wall crest deformation and these formulae were tested against case history data. This led to a minor modification to the formulae. The final calibrated empirical prediction formulae provide an estimation of wall movement to ±5mm with 80% accuracy, when compared to the case history data, and >95% accuracy when considering ±10mm, which is considered acceptable for most preliminary engineering designs. The introduction of these formulae will enable engineers to obtain an estimation of wall movement at an early stage without the necessity of carrying out relatively expensive and time consuming numerical analysis.